CT scanners employ dual energy techniques for a variety of applications including those in the medical and security areas. These dual energy techniques require measurements using two sets of input X-ray spectra with different energies. Dual energy scanners are known to generate dual energy X-rays using two focal spots generated respectively by two X-ray tubes operating at correspondingly two different voltages such that the focal spots are staggered with respect to each other. Each tube includes its own cathode and anode, and must be separately powered, and must be separately mounted, aligned, calibrated and maintained.